1. Field of the Invention
This invention relates to cell culture microcarriers for use in the culture of anchorage-dependent cells, particularly to cell culture microcarriers suitable for use in high-density cultivation of the anchorage-dependent cells attached to the suspended or stationary microcarriers.
2. Description of the Prior Art
In recent years, a rapid progress had been made in the culture of anchorage-dependent cells. One of the previous operational techniques employed therefor is a microcarrier system. The microcarriers which have been reported to date are, for example, those formed from a cross-linked dextran matrix such as Cytodex.RTM. (commercially available from Pharmacia Fine Chemicals, Inc.,) and Superbeads (commercially available from Flow Labs, Inc.,), and those formed from cellulose particles such as DE-52 and DE-53 (commercially available from Whatman, Inc.,). However, these microcarriers have a disadvantage that the recovery of desired biologically active substances is very low to an extremely hydrophobic interaction with proteins of diethylaminoethyl (DEAE) groups used therein as functional groups.
Although microcarriers based on polystyrene are also available, they have the same disadvantage as mentioned above because polystylene itself is highly hydrophobic substance.
If base polymers or functional groups having a higher hydrophobicity were used, distensibility or growability of cells would be deleteriously effected in a low serum condition, which might even lead to death of the cells.
An aspect of the present invention is to provide cell culture microcarriers which can be produced economically.
Another aspect of the present invention is to provide cell culture microcarriers having a low non-specific absorbing property for proteins and being capable of effectively recovering desired biologically active substances produced by animal cells.
A further aspect of the present invention is to provide cell culture microcarriers which can be used in a low serum condition.
Thus, the cell culture microcarriers according to the present invention consist of water-insoluble polymer particles constituted by (meth)acrylic ester, the particles having an average diameter of 100-1,000 .mu.m and a density of 1.00-1.20 g/ml in a culture medium as well as positively chargeable chemical moieties distributed at least on their surfaces, the moieties being introduced thereinto by the reaction between the above ester and ammonia or amine having 5 or less carbon atoms.